Most heating pads are designed to go under the tank not on the side. There needs to be a space between the pad and the glass otherwise the glass may crack if it gets wet. The exception to this is the stick-on style of heating pad which can go right on the glass.

As for the bulbs, they are generally not a good idea for frogs as they can dry the frog out. But if you spray the substrate daily, and have a very moist tank, bulbs can work too, but you have to keep on top of it so you maintain the humid conditions.

Make sure whatever type of heating you use, that you take the temperature reading where the frog is, not at the top of the tank.